(华南理工大学 国家金属材料近净成形工程技术研究中心，广州 510640)
摘 要: 基于高分辨率三维X射线断层扫描技术，对实际ADC12铝合金压铸件疲劳试样内部微观孔洞进行了检测和重构，对 7组不同孔隙率的试样进行了5级应力水平的高周疲劳实验。三参数Weibull分析表明：随着应力水平升高，疲劳寿命分散性逐渐降低。采用SEM 观察疲劳断口，确定诱发疲劳裂纹起源的孔洞，并对其进行了分析；基于断口表面的孔洞特征以及X射线断层扫描重构数据，建立了孔洞-疲劳寿命预测方程，并与实验结果进行了对比分析。将三维X射线断层扫描重构数据与有限元分析相结合，计算和分析了实际微观孔洞引起的应力情况，为研究材料内部实际微观孔洞特征对性能的影响提供新的途径。
关键字: 铝合金；高压压铸；微观孔洞；疲劳；三维X射线断层扫描；有限元分析
（National Engineering Research Center of Near-net-shape Forming for Metallic Materials,
South China University of Technology, Guangzhou 510640, China）
Abstract:The micro-porosities in fatigue specimens obtained from practical ADC12 high pressure die castings were detected and reconstructed with high resolution X-ray computed tomography technology. The high cycle fatigue tests were carried out at five stress amplitudes on seven groups of the specimens with different porosity contents. The Weibull analysis suggested less scatter of the fatigue life at larger stress condition. With the SEM observation on the fatigue fractured surfaces, the porosities initializing the fatigue cracks were identified and measured. A pore-fatigue life prediction equation was deduced with the pore characteristics from the fracture surface and 3D X-ray tomography inspection. With 3D reconstruction of tomography data and FEA method, the simulation of the stress distribution around the actual 3D pores were carried out and analyzed further. A new approach was provided to assess the effect of pores with actual 3D characteristics on casting properties.
Key words: aluminum alloy; high pressure die casting; micro-porosity; fatigue; three dimensional computed tomography; finite element analysis
